Washing machines are typically equipped to operate with one or more modes or cycles such as wash, rinse, and spin modes. During a wash or rinse mode for a vertical axis washing machine, the laundry articles are usually submerged at least partially within a wash or rinse fluid while an agitator is used to impart motion to the laundry articles that are contained within a wash basket. A wash tub contains the fluid, agitator, and wash basket.
During a wash or rinse mode, the wash basket remains stationary while the agitator rotates to impart movement to the laundry articles. During a spin mode, typically both the agitator and the wash basket are rotated so as to subject the articles in the laundry to centrifugal forces. These forces cause water and other fluids to be wrung from the clothes. These liquids can exit the wash basket through holes positioned along the outer wall of the wash basket for subsequent removal from the wash tub.
For operation of the washing machine appliance between the wash, rinse, and spin modes, it is desirable to independently control the movement of the agitator and wash basket. More specifically, during the wash and rinse modes, the wash basket may be held stationary while the agitator is rotated so as to impart movement to the laundry articles. During the spin mode, however, rotation of the wash basket is required to wring liquid from the articles as set forth above.
In order to control the rotation of the agitator and wash basket, a vertical axis washing machine can be equipped with e.g., a clutch for engaging and disengaging the wash basket from a motor that can be used to rotate the agitator and/or wash basket. As the washing machine executes a cleaning process, the clutch is operated at certain times in order to provide the desired movement of the agitator and wash basket during one or more wash, rinse, and/or spin cycles. To prevent damage to the appliance, proper engagement and disengagement of the clutch during operation is desirable.
Certain challenges are presented in properly engaging and disengaging the clutch. By way of example, once a wash, rinse, or spin cycle is completed, clothes or other articles in the wash basket can place a torque on wash basket and/or agitator. In turn, this torque is transferred against the clutch and can increase the friction that must be overcome to shift or move the clutch. A spring or other positioning mechanism may not be able to provide enough force against the clutch to overcome this friction.
Thus, in order to free the clutch, the motor can be jogged or bumped. More specifically, the motor can be energized for a short period of time to partially move the rotor in an effort to release the clutch. However, after the clutch is released, its position relative to e.g., to other components may change because the clutch may rotate after it is released. Furthermore, the amount of rotation may vary each time this procedure is used to free the clutch. As a result of this rotation, the clutch may no longer be properly aligned for receipt by e.g., a platform lock or other holding feature of the appliance. A similar problem may occur when attempting to reengage the clutch with the motor-i.e. after jogging, the clutch may not be properly aligned to engage the motor.
The failure to properly align the clutch when attempting to shift it between various modes of operation can cause damage to the appliance such as e.g., destroying the clutch and/or other components of the appliance. For example, if the clutch is not properly engaged with the motor and a spin cycle is initiated, the clutch may attempt to engage after the motor has reached high speed. At the moment of this attempt, all of the rotational inertia of the loaded wash basket is encountered by the motor, which generally will result in damage to the appliance.
Accordingly, a washing machine appliance that can shift between various modes or cycles of operation would be useful. More particularly, a mechanism or assembly for positioning the clutch of a washing machine appliance so as to determine the relative motion of the agitator and wash basket between various modes of operation would be beneficial. Such a mechanism that can be operated in a manner that provides for proper alignment of the clutch when engaging or disengaging the clutch from the motor would be particularly useful.